Method for concrete mixtures



Oct. 9, 1928.

J. D. POWELL METHOD FOR CONCRETE mxx'run'as Filed 0ct. 25, 1926 s Shets-Sheet 1 Im H lNVENTOR. M 17, I

Oct. 9, 1928.

I 1,687,227 J. D. POWELL METHOD FOR CONCRETE MIXTURES Filed Oct. 25; 1926 5 Sheets-Sheet 2 Oct. 9, 1928. 1,687,227

J. D. POWELL METHOD FOR CONCRETE MIXTURES 5 Sheets-Sheet 5 Filed 001.. 25, 1.926

Oct. 9, 1928.

.J'. D. POWELL METHOD FOR CONCRETE MIXTURES 5 SheetsSheet 4 Filed Oct. 25 1926 w/gamala Oct. 9, 1928.

i J. D. POWELL METHOD FOR CONCRETE MIXTURES Filed Oct. 25, 1926 5 Sheets-Sheet 5 NOW w on womim 10M 9w 1 i wmaw new WW m6 NQM mvQw.

Fatented Get. 9, 1928.

PATENT OFFICE.

JOHN D. POWELL, OF CINCINNATI, OHIO.

METHOD FOR CCNCRETE MIXTURES.

Application filed October 25, 1926. Serial No. 144,044.

My invention relates to concrete mixtures, and is exemplified in connection with concrete which contains aggregates, and is also applicable for similar mixtures containing cement or quickly settable ingredients, and 1s intended for use primarily in building operations employing concrete, including dams, abutments, piers, as well as road work, and for other purposes.

It has heretofore been the practice in building operations to haul the gravel, crushed stone or other aggregate. the sand, and the cement, to the site at which the concrete was to be used, the mixing of the concrete taking place at this site, and the concrete being poured or utilized immediately after mixing the ingredients with the water, it being necessary in such practice further to erect or instal a mixing plant at the site in order to permit the mixing to take place thereat.

I have found that draw-backs to this character of operation have been, that the mixing of the various batches of concrete were not uniform that the amount of mixing imparted to the various batches was likely to be and very often was not sufficient, with the result that the concrete was not thoroughly mixed, was not uniform, and did not set properly or with sufficient strength; and that there was a great waste of materials; and furthermore that the mixing plant took up valuable space at the site and was in the way of others of the building operations.

These objections were especially prevalent in large structures and in constructing concrete buildings. On the other hand if the j ob was small, the hauling of the separate materials was relatively expensive, the expense of the transportation of a concrete mixer to the site was out of proportion to the value of the work, and if manual mixing was resorted to, this was slow and also expensive. Furthermore, great waste in left-over ingredients occur under the methods now in general use.

It is theobj ect of my invention to avoid the objections incident to the methods now in general use of mixing concrete at the site, and to avoid the necessity of employing mixing devices at the site; further, to provide a method whereby the concrete is mixed at a mixing plant, where mixing devices of large capacity are installed, and where the ingredients and proportions of ingredients entering into the mixture can be readily supervised and accurately determined; further, to transport the mixture in batches from the plant to the site at which the concrete is to be utilized, which site may be at a considerable distance and a number of miles from the mixing plant and be for instance thirty miles distant therefrom, and the transportation may extend over a considerable period of time and ma for instance consume an hour in making the delivery from the plant to the site, these distances and times being given merely as examples, as the same may be greater or less in practice.

I further contemplate that agitation of the concrete mixture shall take place during the transportation and preferably throughout the time of transportation, whereby thorough mixing and conditioning of the concrete is insured and a setting of the mixture is avoided. The transportation preferably takes place in aclosed vessel in which the concrete is subjected to agitation.

The concrete mixture is to be dumped on arrival at the site for utilization. Sufficient transportation is provided for insuring a continuous supply of wet concrete mixture throughout the time that the same is to be utilized so that successive batches of the concrete mixtures delivered will set as an integral body. This is especially applicable for large structures or large work. on the other hand only suflicient concrete need be transported in small work as is necessary for the work; furthermore, concrete mixtures of different fluidities or densities may also be mixed at the plant and transported and delivered at the site so that the particular kind of concrete mixture desired may be supplied by employment of my invention.

It is a further object of my invention to I heat ingredients of the mixtures whereby to enhance the mixing properties of the same during cold weather and to prepare the mixtures for transportation through the cold, and, further, to insulate the mixtures being transported from the cold so that the mixtures are delivered at the site in heated condition for being poured or utilized while still in heated condition, I

I have illustrated an exemplifying means which may be employed in performance of my improved method, but do not wish to be limited to any of the means shown in performing the method, as other means may be employed, or the performing my improved metho within the scope of my invention stated in the appended claims.

In the drawings of the exemplifying apparatus:

Fig. 1 represents a vertical longitudinal section of an exemplifying mixing plant, taken in the plane of the line 1-1 of Fig. 4, the mixers being vation.

Fig. 2 is an end view of one of the chutes and gate therein.

Fig. 3 is a cross section ofthe means for driving the mixer, taken on the line 33 of Fig. 7, and partly broken away.

F ig. 4 is a vertical crosssection of the same,

taken 1n the plane of the irregular line 44 of Fig. 1.

Fig. 5 is an end view of partly broken away.

Fig. 6 is a horizontal plan section of the same, taken in the plane of the line 66 of Fig. 1.

Fig. 7 is a side elevation of the mixer and its measuring and control devices, partly in section and partly broken away.

Fig. 8 is a sectional detail view of the same, taken on the line 8-8 of Fig. 7.

Fig. 9 is a sectional detail view of the same taken in the plane of the line 9-9 of Fig. 7.

- Fig. 10 is a detail view of the float valve.

Fig. 11 is a side elevation of the conveying agitator unit; showing the tank in normal position. I I

Fig. 12 is a side elevation of the same, with the agitator tank shown in elevated or dumping position.

Fig. 13 is a vertical cross-section of the same, taken in the plane of the line 1313 of Fig. 11.

Fig. 14 is a longitudinal cross-section of one of the hoppers,

' the same, taken in the plane of the line 14-14 of Fig. 13.

Fig. 15 is a detail view in cross-section, taken on the line 15'15 of Fig. 14.

Fig. 16 is a plan view of one of the stirrer blades, the shaft for the same being partly broken away.

Fig. 17 is a cross-section of the same, taken on the line 1717 of Fig. 16, and,

Fig. 18 is a cross-section of the same taken on the line 18-18 of Fig. 14.

I do not herein claim the exemplifying apparatus herein shown and described, having shown, described and claimed the same in a copending application for patent on improvements in concrete transporting vehicle, filed May 18, 1927, Serial No. 192,275, which is a division of this application.

In the exemplifying apparatus which may be employed in performing my improved method, 21 represents a mixing plant, and 22 represents a transporting and agitating unit.

shown in front end ele-.

a hopper 26 for the sand. These hoppers are arranged as reservoirs for these materials.

The lower ends of the hoppers are shown provided with downwardly converging bottoms 27, 28.

Pipes 31, 32 communicate with the lower end of the hopper 25 at one of their ends, the'pipes sloping downwardly from these latter ends into adjacency 34, which serve mixers 35, 36. The pipes are arranged to discharge gravel, crushed stone or other aggregate which may be used for the concrete, from the reservoir hopper 25 to the mixer hoppers 33, 34, of the respective mixers, said pipes by gravity. Gates 37, 38, in said respective pipes control the flow of said materials into said respective mixer hoppers.

Each of these gates may be to its pipe by a pivot 39. edge of the gate slides in an arcuate slot 40 formed at the end of the pipe. The gate is provided with an operating handle 41.

Each of the mixer hoppers is provided with marks shown as interior ribs, for measuring the ingredients received in the hoppers.

Pipes 44, 45, convey the sand by gravity from the reservoir hopper 26 to the respective mixer hoppers 33, 34. One of the ends of each of these pipes communicates with the lower end of the reservoir hopper 26, and the pipes slope downwardly, the other ends thereof being in adjacency to the mixer hoppers 33, 34. The sand flows through the pipes by gravity. Regulating gates 46, 47, are located at the lower ends of said pipes. These gates are constructed and operated similar to the gates 37, 38.

with hoppers 33,

ich serves as a reservoir for i the said material passing through a plate pivoted he swinging.

The respective reservoir hoppers are elevated, being shown on substructures 51, 52, which may be of concrete, respectively comprising posts 53, 54, and outer Walls 55, 56. The substructures form cement sheds 57, 58. A mixer shed 59 is located between the substructures, the outer walls 55 being continued across said mixer shed. The mixer shed is shown provided with a roof 60. Suitable windows may be provided in the walls 55, 56, for light, ventilation and observation. Endless conveyors 62, 63, are provided for conveying the sacks of cement from the cement sheds at the respective sides of the mixers to an operators platform 64, at the rear ends of said mixers,

Each of the endless conveyors comprises an endless conveyor belt which has conveying cleats thereon. The belt is arranged loopwise about pulleys 65, 66,'respectively fast on shafts 67, 68. The shaft 68 is ournaled in bearings 71 on brackets 72 fixed to the operators platform. The shaft 67 is journaled in for rotating bearings 73' on stands'74 fixed to the floor 75 of the cement shed. The shafts 68 are suitably driven, as by having bevel gears 76 fixed to said respective shafts.

Bevel gears 7 7 mesh with the bevel gears 76 and are fixed to a shaft 78 journaled in bearings 79 fixed to the operators platform and having a pulley 80 fixed thereto. A belt 81- is received about the pulley 80 and a pulley 82 on the rotor shaft 83 of an electric motor 84, fixed to the floor 75 of the operators shed. The rotor shaft may have an outer bearing 85 fixed to said floor. A suitable electric control switch 86 may be provided on a stand 87 at the operators .plat-. form M'so the operator thereon may control the operation of the motor. I

The mixers 35, 36, .may be of any suitable construction, and are each shown as comprising a mixing barrel 88, which has a ring gear 89 fixed thereto. The barrel and ring gear are rotatable in a trunnion ring 90.

The trunnion ring has a'ntifriction rollers 91 journaled thereon. These rollers are arranged at suitable points at the side, lower portion and upper port-ion of the ring gear for supporting the ring gear and barrel, and the rollers are provided with end flanges 92 for locating the ring gearand barrel enclwise. Thetrunnion ring is provided with a trunnion 93 at each nions are journaled in bearings 91 of the side frames 95 of the mixer frame.

A pinion 96 meshes with the ring gear 89 the barreli This pinion is located at one side of the barrel. This pinion is fixed to a shaft 97 journaled in a bearing 98 on a housing 99, at the same side of the barrel. A gear 100 is fixed to this shaft. A gear 101 meshes with the gear 100. The gear 101 is fixed to a shaft 102 journaled in the housing and in an axial bore 103 of the trunnion at the same side of the barrel. This construction provides rotative means for the barrel and permits the barrel to tilt while maintaining the driving relation in the gearing, the gear 100 swinging about the axis' of the gear 101. The axes of the trunnion and the shaft 102 are coincident.

The shafts 102 of the respective mixers are provided with pulleys 10 1. Belts 105 are received about said pulleys and the pulley 82 driven by the electric motor 84..

Each mixing barrel is provided with suitable mixing ribs extending in suitable direc-. tions along the inner face of its'wall for cansingmixing movements of the materials in the barrel during rotation of the barrel.

The tilting movement of the mixer is accomplished in the present instance by providing the housing 99 with an extension forming a worm segment 106, which meshes with a worm 107 'on a worm shaft journaled in hearings on the frame. The worm shaft has a bevel gear 108 fixed thereon which meshes gear, for tilting side thereof. These trunwith a air of bevel gears 109, 110, loosely mounte on a cross shaft 111. A clutch collar 112 is keyed to the shaft and slidable thereon for engaging the clutch teeth of either bevel the mixer forward or back. The cross shaft has a pulley 113 fixed thereto. A belt 114 drives the pulley from the pulley 82.

A shifting lever 115 extends tors platform and is pivoted to the frame of. the operators platform at 116. The shifting lever has a fork conhection 117 with. the fork lever 118, said fork lever is pivoted to the frame at 119 and has a fork 120 engaging the clutch collar 112 for shifting the clutch collar.

The proper proportions of gravel, crushed stone or other aggregate, as well as sand, and cement, are fed into the mixer hopper.

The aggregate is for instance fed into the mixing hopper, as by opening one of the gates 37 38, until the aggregate reaches a desired height, gaged by indicating marks 121, shown as ribs, for proper proportion thereof with relation to the batch of concrete to be mixed. The aggregate may, if desired, be spread in the hopper by the operator for leveling the same with relation to the gage as the aggregate flows into the hopper. The gate is rlosed at the proper moment for stopping fiow of the aggregate into the hopper.

The sand may be fed into the mixer hopper in similar manner, and its quantity and proportion determined in similar manner, the sand gate being closed at the proper moment for stopping the flow of the sand.

The cement may be placed into the mixer hop-per by the operator and its quantity and proportion determined in similar manner, or its quantity and proportion may be determined by the number of sacks or parts of sacks of cement placed in the mixer hopper.

The dry mixture is preferably discharged from the mixer hopper into the mixer, the water being added in the mixer.

The discharge from the mixer hopper into the mixer is shown obtained by opening a gate 122 in the bottom of the hopper. This gate is slidable in guideways 123 in the hopper. An operating lever 12 1, convenient to the operator on the operators platform, is pivoted at 125 to a stand on the platform, and extends through a slot 126 in said platform,

' being articulated at its lower end with a link 127. in turn articulated with the gate 122.

The mixture discharges from the hopper into a chute 128, pivoted at 129 to the lower end of the hopper. connects with the inlet 130 of the mixer, so as to feed the mixture by gravity through said inlet into the mixer, the mixture 'being further urged into the mixer by the rotation of the mixer. The pivoting of the chute permits the mixer to be tilted without destroying the connection between the chute and the mixer.

to the opera- The lower end of the chute automatically close,

. barrel, the valves 146,147,

by a float 137 the water closing the valve when Water is shown added to the mixture in the mixing barrel, being fed into the barrel by means of a flexible pipe 131, shown as a hose, having attachment with a pipe 132. The end of the flexible pipe may remain in the barrel during tilting of the barrel. The pipe 132 is an outlet pipe from a tank 133, in which a desired quantity of water in the proper proportion desired for properly mixing the charge in the barrel, is arranged to be stored for discharge into the barrel at the proper moment. The amount of 'water stored in the tank for a charge may be regulated according to marks 134, shown as ribs, on the inside of the tank, for determining the level of water for a charge in the tank.

An inlet pipe 135 is arranged to feed into the tank. The inlet pipe is arranged to be automatically closed by a valve 136, when the desired level of water in the tank has been obtained. This valve is arranged to be operated automatically in any desirable or usual manner upon the water reaching the desired level, such means being adjustable for different levels of water. Thus the inlet valve maybe a usual valve arranged to be closed raising the float for the desired level of water in the tank has been reached. The float is on an arm 138.-

The adjustment is shown obtained by changing the angle of the arm in a vertical plane with relation to the valve 136. Thus the valve 136 has an operating arm 139. The arm 138 is shown as having a plate 140 rigid there with, which is pivoted at 141 to the arm 139. The plate is provided with an arcuate slot 142. A bolt 143 extends through the slot and is threaded into the arm 139 for clamping the plate 140 and arm 138 in various adjusted angular positions with relation to the arm 139.

l/Vhen the desired level of water shall have been obtained in the tank, the valve 136 will so that a charge of water is located in the tank ready for discharge into the mixer barrel.

The pipes 132, 135, are respectively provided with valves 146, 147, provided with operating levers 148, 149, connected together by a cross bar 150, so as to operate said valves in unison. The valves are so relatively arranged that when the valve146 is opened, the valve 147 is closed, and vice versa.

If therefore it is desired to empty the charge of water in the tank into the mixing are operated by the operator on the operators platform, for opening the valve 146 and closing the valve 147 whereby the charge of water descends by gravity from the tank into the mixing barrel. After such discharge the valves 146, 147, are again operated, in reverse direction, for closing the valve 146 and opening the valve 147, whereby a new charge of water of predetermined amount is fed into the tank.

The water introduced to the mixture may be heated, as by steam introduced into the tank 133'by means of a steam pipe 151, having a valve 152 therein for controlling the steam.

The gravel, crushed rock or other aggregate, is charged into the reservoir hopper 25, and the sand is charged into the reservoir hopper 26, preferably by elevating mechanism, from pits 155, 156, the pit 155 being arranged in rear of the reservoir hopper 25, and the pit 156 being in rear of the reservoir hopper 26. The aggregate and the sand are dumped into said respective pits, as from railway dump cars, one of which is indicated at 157, located on tracks 158 supported by ties 159, the respective ends of which are mounted on the respective walls of said pits, and have space therebetween through which the aggregate and the sand are respectiv ely dumped, when the usual dump doors of the dump cars are opened. Other means may be provided for feeding the pits with aggregate and sand respectively, as by means of selfpropelled trucks, barges or other vehicles, as will be readily understood.

Conveying mechanisms 161, 162, are provided for said respective pits. conveying mechanisms may comprise an endless conveyor comprising a belt 163, to which elevating buckets 164 are secured. The belt is formed loopwise about pulleys 165, 166, at its respective upper and lower ends. The stretches of the belts are shown slantingly arranged, the loading stretch thereof being supported at an intermediate point by a pulley 167 on a shaft journaled in brackets 168 extending from the wall of the reservoir. The pulley 1166 is suitably rotatably journaled in the pit.

The conveying mechanisms are driven in suitable manner. Each of the conveying mechanisms is shown operated by an electric motor 171,-the rotor shaft 172 of which has suitable driving connection with the shaft to which the upper pulley 165 of the conveying mechanism is fixed. his shaft is journaled in bearings of suitable brackets 173 extends mg from the roof structure of the material reservoir. The electric motors may The mounted on suitable platforms 174. roof may extend over the motor and platform. Suitable electric control switches 175, 17 6,,may be provided on the wall 55 at the loading platform 185 so that the operator thereon may control the operation of the respective motors; r

The material is received from the loading buckets at the upper end of the conveyor into a chute 181, held in the upper end of the reservoir and discharging into the reservoir. A gate 182 hinged to the chute at 183 automatically closes the chute when no material is passing therethrough so as to maintain the heat in the material reservoir. The gate is Each of these the weight of the material pus form, and transferred to the cement by valves 199, 200.

by gravity, ing the gate sufficiently for operating the same.

A loading platform 185 is provided for the cement sheds, adjacent to the tracks. The adjacent walls of the respective cement sheds are provided with openings normally closed by doors 186. The. cement may be receive from cars on the tracks, or from other suitable vehicles, loaded on to the loading platsheds.

The reservoir hoppers are provided with roofs 187 for protecting the contents from the elements, and the hoppers are preferably closed structures, access being had to the interior of each of the same through an opening 188, normally closed by a door 189, a lad der 190 extending from the opening downwardly inside the reservoir hopper. The platform 174 may be at the outside of the door 189, to which access may be had by climbing the conveyor buckets 164. The roofs may extend outwardly over the platform.

Each of the reservoir hopper structures comprises walls 191, 192, respectively connected by tie-rods 193, 194. The walls are preferably heat insulated, as by insulating layers 195, insulating layers 196 being located under the roof.

Heating pipes 197,

arranged to close automaticall 198, extend along the inside of the walls. Steam may be circulated through these pipes from a suitable steam heating plant, the heat being controlled The object of providing the heating means is to heat the materials in cold weather so that heated ingredients may be introduced into the mixtures and a heated mixture obtained. The water may also be heated as hereinbefore described.

The concrete or other mixture made at the mixing plant is conveyed in batches to the site of operation at which the mixture is to be used, which site may be distanced in any direction from the mixing plant any reasonable distance, occupying any reasonable duration of time for conveying the mixture to the site. This site may for instance be located as much as thirty miles distant from the mixing plant, and the transportation of the mixed materials to the site may as an example occupy as much time as an hour, although these distances and durations of time may be greater or less.

The mixture is received from the mixing plant and conveyed in batches, as by a wheeled conveyance and preferably in a closed container, to the site, the respective batches of the mixture being agitated during such travel.

As a convenient means of transportation I have exemplified a motor truck 205, the propelling means of which may be a suitable usual internal combustion engine 206, or other suitable propelling means, having suitable d tied by the operative connections with the rear wheels 207 for rotating the same, and provided with usual suitable clutch, brake and speed changing gearing, brake operating means, speed control means, and usual other control means for the engine, as well as. steering means, the latter exempli-- steering wheel 208, for steering the front wheels 209 of the truck, usual springs being interposed between the axles of the wheels and the chassis 210 of the truck in usual manner.

The traveling container, shown as a tank 211, is mounted on the truck, and is provided with agitating means for agitating the mixture, which is arranged to be charged into the tank from the mixers. This agitation of the mixture during conveyance of the same causes the mixture to be stirred and thoroughly blended and conditioned, and pre-' vents the setting of the same.

The truck is arranged to be driven into a pit 212 lower than the mixers 35, 36. The container on the truck is provided with a charging opening 213, normally closed by a closure 214, shown as a plug having frustoconical connection with a closure ring 215 on the tank. This closure plughas articulating connection with a closure strap 216, as by means of links 217, articulated with said strap and said plug. The strap is pivoted at 218 to the tank at one of its ends, and is provided with a fork 219 at its other end, in which a screw 220 is received. The screw is pivoted to the tank and is arranged to be releasably received in the fork. A wing nut 221 is received about the screw for clamping the strap and the closure plug toward the closure ring.

The truck is placed in the pit so that its opening 213 is in line with the discharge 222 of one of the mixer barrels. Chutes 223, 224, are located under the respective mixin barrels. The discharge from the mixing barrel into the charging opening 213 on the truck takes place by gravity along one of these chutes. The capacity of one of the mixing barrels is preferably sufiicient to fill the tank on a truck suflicientlyfor a load. The capacity of the respective mixing barrels may be greater or less than a load as desired. A load is preferably one-half the cubic contents of the shell, although such load may be greater or less as desired. If a small quantity of the mixture only is to be transported, only sufiicient to amount to the quantity desired is loaded into the shell. Sufiicient space is however left-in the tank under all loaded conditions to permit proper agitation of the mixture during transportation. I

The agitating of the mixture in the tank is shown accomplished by means of a stirrershaft 231, extending lengthwise of the tank, from which stirrer blades 232 extend. These stirrer blades are preferably of greater width than thickness, and are preferably adjustas well as clutch operating and able on the shaft, so that their paths through the material may be wider or narrower as desired, and so that further they sented at different inclinations in their paths of travel for im arting endwise movements to the mixtures; urthermore, the blades may be adjusted to opposite angles so that some of the blades will present one of their faces as an advancing face and the other blades present the other'of their faces as advancing faces, and thereby move the materials in opposite directions.

The adjustment of the blades may be accomplished by providing hubs 235, which are secured to the shafts at suitable points, as by bolts 236. The hubs may be adjusted lengthwise of the shaft, suitable spline groove and key connections 237 being'between the hubs and the shaft. Each of the blades is provided with a flange 238, and a stem 239 received in a centering hole 240 in the hub. Bolts 241 are received through arcuate slots flange 238, and are threaded into the hub, for clamping the flange to a coacting face on the hub at the desired inclination.

Adjustments of the blades may be made by a man entering the tank through the chargin opening 213, which serves as a manhole.

e tank comprises a shell 245, which is preferably cylindrical in cross-section, and is provided with heads 246, 247, which may be made releasable from the shell.

The stirrer-shaft 231 is journaled in bearings 248, 249, in the heads. These bearings include stuffing boxes 250, to prevent leakage between the shaft and its bearings. The shaft "is also journaled in a bearing 251 on a stand 252 extending rigidly from a platform 253. The platform is provided with brackets 254, by means of which the tank is fixed to the platform. The tank is fixedly held endwise to the platform and also to prevent its rotation on the platform.

11 engine 255 is mounted on the platform, and is exemplified as an internal combustion gasoline engine.

A driven shaft 257 is journaled on the engine frame and in the hub 258 of a sprocket wheel 259 journaled in a bearing 260 of the stand 252. This drivenshaft isdriven at suitable speeds from the crank shaft of the engine as by means of speed changing mechanism in a suitable gear box 261, from which a usual suitable wiggle stick 262 extends for changing the speed relation and direction of rotation in the gearing. This wiggle stick is pro vided with a handle 263 which may be operated by the driver through the rear opening 264 in the cab 265 of the vehicle.

One of the clutch collars of a suitable clutch 266 is fixed to said shaft. The other collar of said clutch is slidable axially on the hub 258 for engagement or release of the teeth of said clutch; this latter collar having spline groove and key connection with said hub. A lever may be pre-' stand 252 and is A gasoline or other fuel tank 272 and a water tank 273 may also bemounted on and be movable with the platform and have suitable connections with the engine 255. r

A chain-belt 274 is received over the sprocket-wheel 259 and a sprocket wheel 275 fixed to the agitator shaft 231 for driving the agitator shaft from the engine 255. The agitator shaft is held in endwise relation in its earings.

When the mixture has been charged into the tank, the tank is closed by the closing of the door plug 214 and clamping of the same in position, and thereby excluding outside air from the mixture, it being understood that the outlet opening has been previously closed prior to charging.

In order to retain the heat of the mixture, when the mixture has been heated during cold weather, the tank 211 is insulated, as by surrounding the same with a heat insulating jacket 276, and providing its heads with heat insulating layers 277, 278.

The engine 255 is provided with suitable usual controls for insuring its continuous proper operation, indicated by levers 281, 282, 283, for instance, controlling the starter 284, the ignition, and the gas supply, which controls are accessible to the driver of the ve hicle while situated in the cab 265, as by reach ing through the rear open-ing 264 in said cab.

These levers may be mounted on an instrument board 285 extending from the stand 252. The levers 281 and 282 respectively control suitable usual electric connections in the starting and ignition devices for the engine 255, and the lever 283 has usual operative connection with the usual fuel controls of an internal combustion engine.

The mixture is conveyed in batches in a closed substantially air-tight tank from the mixing plant to the site of use While being stirred or agitated, and at the site of use the mixture is dumped condition for uses for which it may in the building or other operation for it is intended. For conveniently delivering the mixture, the tank is provided with an outlet opening 291 at the lower portion of its rear end, which outlet opening is preferably in the head 247.

The head is provided with a door ring 292 at said opening. A closing plug 293,, which preferably has a frusto-conical closing joint with said door ring, is arranged to close said opening. It is articulated with a clampin strap 294 by means of links 295 articulated be put which in homogeneous and livewithsaid strap and said plug. The strap is hinged by a hinge 296 to the tank. A screw 297 is pivoted to the tank and is arranged to be received in a fork 298 at the other end of said strap. A wing nut 299 is threaded over said screw for clamping the strap and the plug toward the door ring.

For convenience in dumping, suitable hoisting means are provided for the tank, preferably operated bv the vehicle engine. The rear end of the tank is preferably hinged to the chassis 210 of the truck, as by means of hinges 301 between the rear ends of the platform 253 and said chassis, at the respective sides of said platform and chassis.

The platform is provided with a depending arc piece 302 at each side thereof. These are pieces are rigidly fixed to the platform. A

ousing 303 extends crosswise of the chassis and has a screw rod 304 extending from its middle. Wheels 305 are received about said shaft at the respective ends of said housing and coact with the arcuate faces of the respective are pieces depending from the platform.

The shaft also has wheels 306 thereon 'at its respective ends which coact with tracks 307 extending lengthwise of the chassis at the respective sides of the latter and rigidly fixed to the chassis. The wheels 305 and 306 have flanges 308 therebetween for locating said wheels endwise.

The screw rod is slidable endwise in bearings 311, 312, 313, fixed to the chassis. A nut 314: is threaded to the screw rodand is held endwise between the bearings 311, 312. The nut is provided with a pinion 315 which is arranged to be driven by a gear 316 meshing therewith. This pinion is normally loose on a driven shaft 317 extending from the usual transmission case 318 of the truck, and driven selectively at various speeds and in reverse directions by the caring therein, which is in turn driven. by t e truck engine 206.

A clutch 321 is located between said gear 316 and an endwise shiftable clutch collar 322. This clutch collar has spline groove and key connection with the shaft 317.

An operating lever 324 is pivoted at 325 to the chassis, and has a fork 326 provided with pins received in an annular groove327 of the shiftable clutch collar. An operating rod 328 has articulation 329 with said clutch lever, and is provided with a handle 330 at the drivers position for being readily operated by the driver seated in the truck cab.

During dumping of the contents of the tank, the rotation of the agitator blades is preferably continued, for full discharge of the contents of the tank, these contents being especially fluid due to itscontinued and long agitation during travel. After discharge of the mixture, the tank is again lowered into horizontal position.

In order to prevent the formations of a film of set concrete upon the inner face of the wall of the tank or upon the blades, the shaft, and the operative parts in the tank, I prefer to provide the tank with a charge of water, and to continue the movements of the blades in the tank during the return travel of the truck to the mixing plant, where the water in the tank may be discharged and, if desired, used in making subsequent mixtures.

In order that there may be a supply of water continuousl ready for use as soon as the mixture has been discharged from the tank, I provide a supplemental tank 331 on the main tank 211, the same being suitably fixed thereto. A passage 332, which includes a valve 333, is between the supplemental tank and the main tank, for charging the water froin the supplemental tank into the main tan c.

The supplemental tank is provided with a charging opening 334, comprising a closing ring 335 arranged to be closed by a closing plug 336, hingedly pivoted to a clamping strap 337, which is hinged and releasably secured to the supplemental tank 'in manner similar to the hinging and securing of the closing straps 216, 294 with relation to the main tank. The supplemental tank is preferably provided with heat insulation 338 thereabout.

The supplemental tank is arranged to be charged with water at the mixing station prior to leaving of the truck therefrom, and this water will in cold weather be heated water, which is retained heated by the heat insulation about the supplementary tank.

The exhaustpipe 339 from the engine 255 may be caused to pass through the supplemental tank, as shown at 340, for aiding in heating said water or maintaining the same in heated condition.

This water is charged into the main tank by the opening of the valve 333 after the concrete mixture has been discharged from the main tank and the discharging opening thereof has been closed. There is sufficient water charged into the main tank in this manner to cause splashing of the entire interior and operating parts in the main tank during return of the main tank to the mixing station.

I prefer to drive the stirrers in the agitator tank by an independent engine, independent of the engine which drives the truck, so as to relieve the truck engine of this duty, and to further provide for rotating the agitators or stirrers in convenient manner regardless of the positions of the agitator tank.

The delivered mixed and conditioned batches at the points distanced from the mixing plant may be poured directly from the agitator tank into the forms for receiving the concrete, or into a chute communicating with elevating mechanism for conveying the mixture to suitable gravity chutes or forms, as may be desired, for immediate use. A sulficient number of trucks may be employed so that the suppl of concrete is substantially continuous ant in greater quantity than is possible b individual temporary mixing plants, am with the assurance that the concrete produced by my invention and supplied in accordance therewith is of better quality with the same ingredients compared wlth the concrete supplied by the usual temporary mixing plants now in general use, and with the further assurance that the mixed batches are homogeneous and thoroughly stirred and that the strength of the mixtures has been improved by the agitation during their travel to the site of use, and that the mixtures set on the job with maximum solidity and tenacity.

My improved method also insures that more uniform mixtures are produced, and provides a convenient method whereby centralized supervision and inspection of the ingredients entering into the mixtures and the proportions of ingredients may be assured, thereby permitting further economy in that a great number of contractors and architects may unite in employing an inspector for all, whose duty it shall be to properl supervise the mixtures.

y invention also provides a method whereby economy is insured by economical handling of materials, the elimination of duplications of hauling, the elimination of waste of left-over separate ingredients, and the avoidance'of the necessit of having duplicate crews of mixers at t 0 various jobs, which jobs by employment of my invention are supplied with mixed concrete from a contralized station at which the mixing takes place on the large scale in unduplicatcd manner.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is: I

, l. A method for concrete mixtures which comprises mixing the mixturewith heated ingredients into a heated wet-mixture at a locality prior to transportation, then transporting said heated wet mixture in batches and agitating said batches of said heated Wet mixture during such transportation while substantially excluding outside air from said batches of said heated wet mixture during such transportation and agitation, and heat insulating said heated wet mixture during such transportation.

2. A method for concrete mixtures which comprises mixing the mixture with heated ingredients into a heated wet mixture at a-locality prior to transporation, then transporting said heated wet mixture in batches and agitating said batches of said heated wet mixture during such transportation while substantially excluding outside air from said batches of said heated wet mixture during such transportation and agitation, heat insulating said batches of said heated wet mixture during such transportation, whereby to permit locating said transported batches of said heated wet mixture in contact with one another for permitting said batches of said heated wet mixture to integrally set.

3. A method for concrete mixtures which comprises mixing the mixture with heated ingredients into a heated wet mixture in amount equal to a plurality of batches at a locality prior to transportation, transporting said heated wet mixture in batches and agitating said batches of said heated wet mixture during transportation while substantially excluding outside air from said batches of said heated wet mixture during such transportation and agitation, and heat insulating said heated wet mixture during such transportation.

4. A method for concrete mixtures which comprises mixing the mixture with heated ingredients into a heated wet mixture in amount equal to a plurality of batches at a locality prior to transportation, then transporting said heated wet mixture in batches and agitating saidbatches of said heated wet mixture during such transportation while substantially excluding outside air from said batches of said heated wet mixture during such transportation and agitation and heat insulating said batches of said heated wet mixture during such transportation, whereby to permit locating said transported batches of said heated wet mixture in contact with one another for permitting said batches of said heated Wet mixture to integrally set.

5. A method for concrete which comprises mixing the ingredients of said concrete into a wet flowable mixture in amount equal to a plurality otbatches at a locality prior to transportation thereof, transporting said wet flowable mixture in batches while protecting the same from the air and stirring said re spective batches of wet flowable mixture While so protecting the same and while so transporting the same for conditioning the said batches of said wet flowable mixture and preventing setting thereof during transportation thereof, whereby to mix said mixture in amount equal to a plurality of batches in one locality and transport said mixture in batches While agitating and conditioning the same for utilizing said wet flowable mixture in another locality a substantial distance from said first-named locality.

6. A method for concrete which comprises mixing the ingredients of said concrete as a wet flowable mixture in amount equal to a plurality of batches at a locality prior to transportation thereof, transporting said wet flowable mixture in batches to a distant locality while stirring said wet fiowable mixture during such transportation and protecting said batches from the atmosphere duringsuch transportation for maintaining said batches Jill IBU

of wet flowable mixture in flowable condition and maintaining the settable' properties of said respective batches throughout such transportation and for further conditioning said batches, whereby to deliver said wet flowable mixture in batches at said distant locality in flowable condition for permitting use and setting of the concrete'at said distant locality.

7. A method for concrete mixtures which comprises mixing the mixture with heated ingredients into heated wet mixture at a locality prior to transportation, dumping the heated wet mixture, transporting the dumped heated wet mixture in batches and agitating the respective batches of the heated wet mixture during such transportation while substantially excluding outside air from the JOHN D. POWELL. 

